People get married for all sorts of different reasons.
The most common reasons I’ve come across are:
1. Dual income/benefits (this includes marrying for U.S. citizenship)
2. Already have a child together
3. Come from an ultra religious family and think a marriage certificate is the only way to have sex without rotting in hell
4. Want to start a family
5. Believe in true love
The best way to sum up the reason I’m married is in the lyrics of a Christina Aguilera song (because I’m deep like that):
It’s not so easy loving me
It gets so complicated
All the things you’ve gotta be
Everything’s changin’
But you’re the truth
I’m amazed by all your patience
Everything I put you through.
When I’m about to fall
Somehow you’re always waitin’
With your open arms to catch me
You always save me from myself.
Don’t ask me why I’m cryin’
‘Cause when I start to crumble
You know how to keep me smilin’
You always save me from myself.
I know it’s hard, it’s hard
But you’ve broken all my walls
You’ve been my strength so strong
And don’t ask me why I love you
It’s obvious your tenderness
Is what I need to make me
A better woman to myself
You’re gonna save me from myself.
holly pelesky 
love it.